Hepatic Steatosis In Rats Research Articles

Signal transduction mechanism of TRB3 in rats with non-alcoholic fatty liver disease

To evaluate the possible role of Tribble 3 (TRB3) in a rat model of non-alcoholic fatty liver disease (NAFLD) and its signal transduction mechanism. Thirty Sprague-Dawley rats were randomized into three groups: normal control group, non-alcoholic fatty liver group A (fed on a high-fat diet for 8 wk) and group B (fed on a high-fat diet for 16 wk). To determine the degree of hepatic steatosis in rats of each group, livers were stained with hematoxylin and eosin, and evaluated; real-time fluorescent quantitative reverse transcriptase-polymerase chain reaction was performed to measure the expression levels of TRB3 mRNA; and Western blotting analysis was done to determine the expression levels of protein kinase B (Akt) and phosphorylated protein kinase B (p-Akt-Thr308, p-Akt-Ser473). Hepatic steatosis was evident in both NAFLD groups: mild to moderate hepatic steatosis occurred in group A, mainly as mild steatosis. Moderate to severe hepatic steatosis occurred in group B, mainly as severe steatosis. The expression level of TRB3 mRNA in group B was significantly higher than in the control group (122.28 +/- 95.37 vs 3.06 +/- 2.33, P = 0.001) and group A (122.28 +/- 95.37 vs 5.77 +/- 4.20, P = 0.001). There was no significant difference in the expression levels of Akt (1.03 +/- 0.53 vs 1.12 +/- 0.77, P = 0.729) and p-Akt-Thr308 (0.82 +/- 0.45 vs 0.92 +/- 0.38, P = 0.592) between group A and the control group. The expression level of Akt and p-Akt-Thr308 in group B was significantly lower than in group A (Akt 0.41 +/- 0.16 vs 1.12 +/- 0.77, P = 0.008; p-Akt-Thr308 0.47 +/- 0.19 vs 0.82 +/- 0.45, P = 0.036) and the control group (Akt 0.41 +/- 0.16 vs 1.03 +/- 0.53, P = 0.018; p-Akt-Thr308 0.47 +/- 0.19 vs 0.92 +/- 0.38, P = 0.010). The expression level of p-Akt-Ser473 in group A was significantly higher than in group B (1.48 +/- 0.50 vs 0.81 +/- 0.39, P = 0.041) as well as the control group (1.48 +/- 0.50 vs 0.45 +/- 0.26, P = 0.003). TRB3 blocks insulin signaling by inhibiting Akt activation, which contributes to insulin resistance. It may be an important factor in the occurrence and development of NAFLD.

Preventive effects of total flavonoids of Litsea coreana leve on hepatic steatosis in rats fed with high fat diet

Aim of the study To evaluate the protective effects of total flavonoids of Litsea Coreana leve (TFLC) on rat high fat diet-induced hepatic steatosis model. Materials and methods Rats were given either a high fat diet alone or the same diet plus TFLC for 4 weeks. Results TFLC improved liver histology with reduced serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), as well as decreased the over accumulation lipids in serum and liver. TFLC increased serum levels of leptin and insulin, while decreased serum TNFα level in high fat diet fed rat. Furthermore, TFLC was found increased the expression of peroxisome proliferator-activated receptor α (PPARα) in high fat diet fed rat liver. These benefits were associated with increased superoxide dismutase (SOD) and decreased malondialdehyde (MDA) in high fat diet fed rat liver. Conclusions TFLC exerts protective effects against hepatic steatosis in rats fed with high fat diet possibly through its antioxidant actions, improving the adipocytokines release and increasing the expression of PPARα.

Taurine supplementation prevents ethanol‐induced decreases in serum adiponectin and reduces hepatic steatosis in rats

Adiponectin (Acrp) has important insulin sensitizing functions and acts to increase fatty acid oxidation in liver. Chronic ethanol feeding (EF) results in hepatic steatosis, associated with decreased serum Acrp, due, at least in part, to a decrease in Acrp secretion by adipocytes. In other model systems, decreased Acrp expression is associated with oxidative stress in adipose. If EF increases oxidative stress in adipose, leading to decreased serum Acrp and contributing to ethanol‐induced steatosis, then treatment with taurine, an amino acid with anti‐oxidant properties, should prevent oxidative stress in adipose and restore Acrp during EF. Male Wistar rats were allowed free access to a 36% ethanol (% calories) liquid diet or pair‐fed control diets supplemented or not with taurine for 1 week. EF increased 4‐hydroxynonenol (4HNE) adducts, a marker of oxidative stress, in both subcutaneous adipose and liver, decreased serum Acrp and resulted in hepatic steatosis. Taurine supplementation prevented EF‐induced 4HNE adducts in adipose and liver, normalized serum Acrp and attenuated liver steatosis. Taken together, these data suggest that oxidative stress in adipose is an important contributor to EF‐induced decreases in serum Acrp and the development of hepatic steatosis. These data also identify adipose as a potential target for therapeutic intervention to prevent ethanol‐induced liver injury.

Fenofibrate prevents orotic acid—Induced hepatic steatosis in rats

The experiments performed in this report were designed to investigate the mechanisms involved in the metabolic alterations associated with orotic acid-induced hepatic steatosis and the effect of fenofibrate, a stimulant of peroxisome proliferators-activated receptor α (PPARα), on these alterations. Male Wistar rats were divided into three experimental groups: 1) fed a balanced diet (C); 2) fed a balanced diet supplemented with 1% orotic acid (OA); 3) fed OA diet containing 100 mg.kg − 1 bw.day − 1 fenofibrate (OA + F), for 9 days. Administration of OA to rats induced significant increase in the hepatic total lipids content, marked microvesicular steatosis and decrease in plasma lipids concentrations compared to control group. Fenofibrate treatment prevented fatty liver induction, caused an additional reduction on plasma lipids concentrations and caused a 40% decrease in the lipogenic rate in adipose tissue. The results also showed a 40% increase in lipoprotein lipase (LPL) activity in adipose tissue from OA treated group and fenofibrate administration induced a 50% decrease in LPL activity. The liver mRNA expression of PPARα and ACO (acyl CoA oxidase) were 85% and 68% decreased in OA group when compared to control, respectively. Fenofibrate treatment increased the PPARα and ACO expressions whereas the CPT-1 (carnitine palmitoyl transferase-1) expression was not altered. Our results have shown that fenofibrate treatment decreases the hepatic lipid content induced by OA which is mediated by an important increase in fatty acid oxidation consequent to an increase in hepatic mRNA expression of PPARα and ACO.

Chronic Administration of Lipopolysaccharide and Proteases Induces Periodontal Inflammation and Hepatic Steatosis in Rats

Epidemiologic studies suggest a relationship between periodontitis and liver diseases. A rat periodontitis model was used to investigate whether a causal relationship exists between periodontitis and liver diseases. Fourteen male Wistar rats (8 weeks old) were divided into two groups: a periodontitis group in which Escherichia coli lipopolysaccharide (LPS) and Streptomyces griseus proteases were applied into the gingival sulcus for 8 weeks, and a control group using pyrogen-free water instead. After blood samples were collected, periodontal tissues and liver specimens were analyzed. Chronic administration of LPS and proteases to the gingival sulcus induced periodontitis and liver injury, including steatosis with inflammation and sinusoidal fibrosis. Apoptosis, enhanced concentration of 8-hydroxydeoxyguanosine, and activated production of tumor necrosis factor-alpha in liver were observed in the periodontitis group, with increased gingival inflammation, serum LPS, and reactive oxygen species. Periodontal inflammation in a rat model induced fatty liver disease through increased serum LPS.

An in vitro study on 5-HT 6 receptor antagonist induced hepatotoxicity based on biochemical assays and toxicogenomics

We investigated the effects of two 5-HT 6 receptor antagonists on rat primary hepatocytes using a combined biochemical and toxicogenomics approach. Both compounds share the same pharmacological target, but displayed strikingly different toxicity profiles in pre-clinical animal studies: While R7199 caused hepatic steatosis in rats, no hepatotoxicity was observed with R0074. Here, we partially reproduced the steatosis findings seen in vivo using primary rat hepatocytes. Biochemical analyses and gene expression results generally supported the findings observed in the animal model and also allowed the differentiation of both compounds with regards to hepatotoxic potential. In particular, the induction of Cyp 2B and Cyp 3A1 directly correlates to the findings in the livers of treated animals. The effects on genes of the steroideogenic pathway relate to the deregulation of cholesterol homeostasis. We also observed the inhibition of β-oxidation, indicating impaired lipid metabolism. Hence, gene expression analysis in combination with biochemical parameters can provide additional insight into the possible mechanisms underlying adverse events.

Protective Effect of Picroliv Against Hydrazine-Induced Hyperlipidemia and Hepatic Steatosis in Rats

The protective effect of picroliv (PIC) obtained from Picrorhiza kurroa (family: Scrophulariaceae) against hydrazine (Hz)-induced hyperlipidemia was evaluated in rats. Hz administration (50 mg/kg, i.p.) caused an increase in triglyceride (TG), cholesterol (CHO), free fatty acids (FFA), and total lipids (TL) in both the plasma and liver tissue of rats accompanied by a fall in phospholipids (PL) in the liver tissue 24 h after its administration, indicating its hyperlipidemic property. The above abnormality was prevented by simultaneous treatment of PIC (50 mg/kg, p.o.) with Hz. Hz treatment also caused an increase in the mobility of TG and TL from adipose tissue, and these results indicate that Hz administration could cause hepatic steatosis by nonhepatocellular factors (such as mobilization of depot fats). This effect was also prevented by simultaneous treatment of PIC with Hz. PIC-alone treatment, however, did not produce any change in the status of all the lipid parameters evaluated in plasma, liver, and adipose tissues. These results indicate that increased mobilization of depot fats from adipose tissue may contribute to the development of hepatic steatosis in addition to decreased lipoprotein secretion, increased hepatic TG biosynthesis, and increased hepatic uptake of FFA. These have been reported as the mechanism responsible for the development of Hz-induced hepatic steatosis. PIC prevents Hz-induced hyperlipidemia, hepatic steatosis, and mobilization of lipids from depot fats, but the mechanism behind the protective effect of PIC remains to be elucidated.

Time course of changes inin vitrolipolysis of intra-abdominal fat depots in relation to high-fat diet-induced hepatic steatosis in rats

The purpose of the present study was to determine the time course of changes in in vitro lipolysis and in perilipin content (Western blot) in the mesenteric and/or the retroperitoneal fat depots in relation to the development of hepatic steatosis in high-fat diet-fed rats. Female Sprague-Dawley rats were submitted to a high-fat diet (HF diet; 42 % as kJ) or a standard diet (SD diet) for 1, 2, 3 or 8 weeks. Fat accretion in the mesenteric and retroperitoneal tissues was higher (P<0.01) in HF diet-fed than in SD diet-fed rats as soon as 1 week after the beginning of the diet. Liver triacylglycerol concentrations were significantly (P<0.01) higher in HF diet-fed than in SD diet-fed rats throughout the experiment, the highest values being reached at week 2 of the diet. Basal and stimulated lipolysis (10(-4) to 10(-7) M-isoproterienol) in the mesenteric and retroperitoneal fat depots was not changed during the first 3 weeks, regardless of the diet. Lipolysis in the mesenteric adipose tissue in the basal and stimulated states was, however, higher (P<0.01) in HF diet-fed than in SD diet-fed rats after 8 weeks of the diets. There were no significant (P>0.05) effects of diet and time on perilipin content of mesenteric tissue. In spite of a rapid fat accretion, the present results do not provide any evidence of a rapid (3 weeks) increase in in vitro lipolysis in intra-abdominal fat depots upon the undertaking of an HF diet at a time where liver lipid infiltration is the most significant.

Effects of ursodeoxycholic acid and/or low-calorie diet on steatohepatitis in rats with obesity and hyperlipidemia.

To evaluate the effects of ursodeoxycholic acid (UDCA) and/or low-calorie diet (LCD) on a rat model of nonalcoholic steatohepatitis (NASH). Fifty-five Sprague-Dawley rats were divided into five groups. The control group (n = 9) was fed with standard rat diet for 12 wk, NASH group (n = 10) was fed with high-fat diet consisted of normal diet, 10% lard oil and 2% cholesterol for 12 wk, UDCA group (n = 10) was fed with high-fat diet supplemented with UDCA at a dose of 25 mg/(kg.d) in drinking water for 12 wk, LCD group (n = 10) was fed with high-fat diet for 10 wk and then LCD for 2 wk, and UDCA+LCD group (n = 15) was fed with high-fat diet for 10 wk, followed by LCD+UDCA for 2 wk. At the end of the experiment, body weight, serum biochemical index, and hepatopathologic changes were examined. Compared with the control group, rats in the NASH group had significantly increased body weight, liver weight, and serum lipid and aminotransferase levels. All rats in the NASH group developed steatohepatitis, as determined by their liver histology. Compared with the NASH group, there were no significant changes in body weight, liver weight, blood biochemical index, the degree of hepatic steatosis, and histological activity index (HAI) score in the UDCA group; however, body and liver weights were significantly decreased, and the degree of steatosis was markedly improved in rats of both the LCD group and the UDCA+LCD group, but significant improvement with regard to serum lipid variables and hepatic inflammatory changes were seen only in rats of the UDCA+LCD group, and not in the LCD group. LCD might play a role in the treatment of obesity and hepatic steatosis in rats, but it exerts no significant effect on both serum lipid disorders and hepatic inflammatory changes. UDCA may enhance the therapeutic effects of LCD on steatohepatitis accompanied by obesity and hyperlipidemia. However, UDCA alone is not effective in the prevention of steatohepatitis induced by high-fat diet.

The effect of ursodeoxycholic acid on hepatic steatosis in rats

The effect of ursodeoxycholic acid on hepatic steatosis in rats

The effect of ursodeoxycholic acid on hepatic steatosis in rats

The effect of ursodeoxycholic acid on hepatic steatosis in rats

Addition of lipid to total parenteral nutrition prevents hepatic steatosis in rats by lowering the portal venous insulin/glucagon ratio.

Hepatic steatosis in rats is associated with an infusion of excessive carbohydrate calories. Previous work from this laboratory suggested that this is associated with an elevated portal insulin/glucagon molar ratio (I/G) and is reversed by parenteral glucagon administration. Although hepatic steatosis is not related to essential fatty acid deficiency, addition of lipid to total parenteral nutrition (TPN) has been reported as being protective against the development of hepatic steatosis. Therefore, we propose that lipid may exert its salutary effect via an alteration of the I/G ratio. To test this hypothesis, adult rats (seven per group) received internal jugular catheters: group 1, saline (3 mL/h) plus chow ad libitum; group 2, 25% dextrose base TPN; group 3, 17% dextrose base TPN + 2.5% lipid; group 4, 25% dextrose base TPN + 2.5% lipid. At 7 days, portal and peripheral venous blood was drawn for insulin and glucagon radioimmunoassay and liver function tests; livers were removed for histology and lipid content determination. Panlobular vacuolization, on histology, and lipid content were excessive in group 2, and the portal I/G was increased because of elevated portal insulin. In contrast, portal venous insulin and I/G did not increase, and hepatic steatosis was absent in groups 3 and 4. The results suggest that the addition of lipid to TPN in rats decreases the portal insulin level and lowers the portal I/G, and thereby prevents hepatic steatosis.

Reversal of hepatic steatosis in rats by addition of glucagon to total parenteral nutrition (TPN): S. Li, M.S. Nussbaum, D.W. McFadden, et al. J Surg Res 46:557–566, (June), 1989

Reversal of hepatic steatosis in rats by addition of glucagon to total parenteral nutrition (TPN): S. Li, M.S. Nussbaum, D.W. McFadden, et al. J Surg Res 46:557–566, (June), 1989

Addition of l-glutamine to total parenteral nutrition and its effects on portal insulin and glucagon and the development of hepatic steatosis in rats

Infusion of total parenteral nutrition (TPN) with excess carbohydrate calories leads to hepatic steatosis in rats and is associated with an elevated portal insulin/glucagon molar ratio. Previously we have shown that adding glucagon to TPN prevents and reverses hepatic steatosis in rats, possibly by increasing hepatic lipid export. It has been reported that steatosis is eliminated in rats by the addition of l-glutamine to TPN. In this study, we examined the effect of glutamine on portal insulin and glucagon levels and the development of hepatic steatosis. Adult rats ( n = 19) received internal jugular catheters: Group 1 ( n = 6), saline (3 cc/hr) and chow ad libitum; Group 2 ( n = 7), 25% dextrose base TPN; Group 3 ( n = 6), 25% dextrose base TPN with 2% glutamine. The infusion rate of TPN was 1.2 cc/100 g body wt/hr. Daily nitrogen balance was determined and at 7 days, portal venous blood was drawn for insulin and glucagon radioimmunoassay, livers were removed for histology and lipid content determination, and the small intestines were removed for mucosal protein and DNA content determination. Panlobular vacuolization of the hepatocytes was noted on histology in Group 2 (TPN) while Group 1 (chow) and Group 3 (TPN + glutamine) showed normal liver morphology. Hepatic lipid content was significantly elevated in Group 2 ( P < 0.05). The portal insulin/glucagon molar ratio was increased because of excessive portal venous insulin in Group 2 (TPN). In contrast, portal glucagon was significantly elevated while the insulin/glucagon ratio and hepatic lipid content did not increase above control levels in the glutamine-supplemented Group 3 rats. The results suggest that addition of l-glutamine to hypertonic dextrose TPN prevents the development of hepatic steatosis, possibly by stimulating glucagon secretion and thus lowering the portal insulin/glucagon ratio and increasing hepatic lipid export.

Reversal of hepatic steatosis in rats by addition of glucagon to total parenteral nutrition (TPN)

Infusion of total parenteral nutrition (TPN) with excess carbohydrate calories leads to hepatic steatosis in rats that is associated with an elevated portal insulin/glucagon molar ratio. Previously we have shown that adding glucagon to TPN prevents hepatic steatosis in rats. In this study we attempted to reverse the steatosis by adding glucagon to TPN after 1 week of TPN alone. Adult rats ( n = 28) received internal jugular catheters: Group 1 ( n = 7), saline (3 cc/h) and chow ad libitum; Group 2 ( n = 7), 25% dextrose base TPN solution for 1 week; Group 3 ( n = 7), 25% dextrose base TPN for 2 weeks; Group 4 ( n = 7), 25% dextrose base TPN for 1 week and then glucagon (15 μg/100 g/day) added to TPN for the second week. The infusion rate of TPN was 1.2 ml/100 g/hr (40% kcal > control). At 7 days (Group 2) and 14 days (Groups 1, 3, and 4) portal and peripheral venous blood levels were drawn for insulin and glucagon radioimmunoassay, blood glucose determination, and liver function tests; livers were removed for histology and lipid content determination. Blood glucose was equivalent among all groups. Liver function tests were within normal limits. Panlobular vacuolization of the hepatocytes was noted on histology in Groups 2 and 3. Hepatic lipid content was significantly elevated in Group 3. The portal insulin/glucagon molar ratio was increased because of excessive portal venous insulin in Groups 2 and 3 ( P < 0.05 by ANOVA). In contrast, portal venous insulin and the insulin/glucagon molar ratio did not increase in Group 4 and hepatic lipid infiltration was absent when glucagon was added to the TPN solution after 1 week of TPN solution alone. The results suggest that the addition of glucagon to hypertonic dextrose TPN is not only protective in preventing hepatic steatosis, but may reverse steatosis, possibly by increasing hepatic lipid export.

Hepatic steatosis in rats fed diets with varying concentrations of sucrose

The role of dietary sucrose concentrations in the development of hepatic steatosis in rats was investigated. Twelve groups of weanling male Sprague-Dawley rats received semipurified diets with different sucrose concentrations ranging from 20 to 50% ( w w ); one group received a cereal-based chow diet. Rats were sacrificed after 3 weeks and body weight, liver/body weight ratio, plasma alanine aminotransferase concentration, hepatic triglyceride concentration, and liver morphology (light and electron microscopy) were determined. Body weight and liver/body weight ratio were decreased in rats receiving 40–50 or 25–35% dietary sucrose compared to rats receiving 20% sucrose or chow. Plasma alanine aminotransferase concentrations were within normal limits. Hepatic triglyceride concentration was significantly increased in rats receiving 40–50 and 25–35% dietary sucrose compared to rats receiving 20% dietary sucrose or chow. Light microscopy showed hepatic steatosis in a periportal distribution at all concentrations of dietary sucrose. Both the frequency and the severity of the steatosis were increased with increasing dietary sucrose concentrations. Electron microscopy from selected livers with increased hepatic triglyceride concentrations revealed increased lipid spheres and increased smooth endoplasmic reticulum without prominent Golgi apparatus or GERL complex. It is concluded that high dietary sucrose concentrations are responsible for the development of hepatic steatosis. Semipurified diets with high dietary sucrose concentrations such as the AIN-76A diet (50% sucrose) should not be used in animal studies in which increased triglyceride deposition could influence experimental outcome.

Hepatic Steatosis in Rats Fed Diets with Varying Concentrations of Sucrose

Hepatic Steatosis in Rats Fed Diets with Varying Concentrations of Sucrose. BACON, B. K., PARK, C. H., FOWELL, E M., AND MCLAREN, C. E (1984). Fundam. Appl. Toxicol. 4, 819–826. The role of dietary sucrose concentrations in the development of hepatic steatosis in rats was investigated. Twelve groups of weanling male Sprague-Dawky rats received semipurified diets with different sucrose concentrations ranging from 20 to 50% (w/w); one group received a cereal-based chow diet Rats were sacrificed after 3 weeks and body weight, liver/body weight ratio, plasma alanine aminotransferase concentration, hepatic triglyceride concentration, and liver morphology (light and electron microscopy) were determined. Body weight and liver/body weight ratio were decreased in rats receiving 40–50 or 25–35% dietary sucrose compared to rats receiving 20% sucrose or chow. Plasma alanine aminotransferase concentrations were within normal limits. Hepatic triglyceride concentration was significantly increased in rats receiving 40–50 and 25–35% dietary sucrose compared to rats receiving 20% dietary sucrose or chow. Light microscopy showed hepatic steatosis in a periportal distribution at all concentrations of dietary sucrose. Both the frequency and the severity of the steatosis were increased with increasing dietary sucrose concentrations. Electron microscopy from selected livers with increased hepatic triglyceride concentrations revealed increased lipid spheres and increased smooth endoplasmic reticulum without prominent Golgi apparatus or GERL complex. It is concluded that high dietary sucrose concentrations are responsible for the development of hepatic steatosis. Semipurified diets with high dietary sucrose concentrations such as the AIN-76A diet (50% sucrose) should not be used in animal studies in which increased trigtyceride deposition could influence experimental outcome.

Effect of apolipoproteins on the induction of hepatic steatosis in rats

The incorporation of apolipoprotein E isolated from human very low density lipoproteins on a triglyceride emulsion produced a substantial increment in hepatic triglyceride after 1 h of in vitro perfusion through the isolated liver of a fasted rat. Both gross and microscopic morphology confirmed a substantial steatosis. Perfusions with triglyceride emulsions which contained no apolipoproteins resulted in a modest increment in hepatic triglyceride although considerably less than emulsions with the E protein, and no morphologic features of steatosis. The steatosis induced in the in vitro perfused fasted livers by the emulsions with E protein could be prevented when CIII-1 apoprotein was also incorporated on the emulsion. A fed rat liver perfused with the E-enriched emulsion accumulated significantly less triglyceride than the fasted preparation. These data suggest that the apoprotein patterns of the plasma triglyceride-rich lipoproteins are of considerable importance for the partition of triglyceride between liver and plasma.

The use of fine-needle aspiration biopsy for the diagnosis of hepatic steatosis in rats

The usefulness and safety of the fine-needle aspiration biopsy (FNAB) technique for the study of liver cell changes were evaluated in rats. Repeated punctures of the same liver lobe (40 punctures in 10 weeks) caused small necroses and hemorrhages which were rapidly organized without significant distortion of the liver structure. Fatty change induced by a high fat diet was recognized in cytological smears stained with Fettrot 7B, and its progression with time monitored. The cytologie findings correlated well with histopathological and biochemical changes observed in the same animals.